I'm building a PC for my sister and just looking for some advice on a processor and anything else. She doesn't do much on it. Just browsing the web and doing homework. I was looking at a P4 but I also seen Celerons. Would they be ok for this? I don't know much about them? Or is there an AMD? She's looking to spend about 600 bucks, and her only request is a decent size HDD.